Postural Hand Synergies for Tool Use

  title={Postural Hand Synergies for Tool Use},
  author={Marco Santello and Martha Flanders and John F. Soechting},
  journal={The Journal of Neuroscience},
  pages={10105 - 10115}
Subjects were asked to shape the right hand as if to grasp and use a large number of familiar objects. The chosen objects typically are held with a variety of grips, including “precision” and “power” grips. Static hand posture was measured by recording the angular position of 15 joint angles of the fingers and of the thumb. Although subjects adopted distinct hand shapes for the various objects, the joint angles of the digits did not vary independently. Principal components analysis showed that… 
Hand synergies during reach-to-grasp.
Much of reach-to-grasp is effected using a base posture with refinements in finger and thumb positions added in time to yield unique hand shapes, suggesting that the CNS uses synergies to simplify the control of the hand.
Digit Position and Force Synergies During Unconstrained Grasping
This chapter investigated the coordinated control of digit position and force in the human hand while grasping and holding a moving object and observed an exponential relationship between finger placement and normal force applied for the thumb and lateral fingers.
Postural variation of hand precision grips by object size
Our two-fold purpose was (i) to quantitatively identify characteristic vectors, i.e., specific combinations of joint angles of fingers, that dominate the posture variation of precision grips in the
Multidigit Movement Synergies of the Human Hand in an Unconstrained Haptic Exploration Task
The results demonstrate that the synergies reported here generalize across tasks, and suggest that they represent basic building blocks underlying natural human hand motions.
Coordination of Hand Shape
Somatosensory and motor information appear to be coordinated in an object-based, spatial-coordinate system, sensitive to orientation relative to gravitational forces, but invariant to grasp forcefulness.
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It appears that the organization of the global pattern of hand muscle activation is highly distributed, which mirrors the highly fractured somatotopy of cortical hand representations and may provide an ideal substrate for motor learning and recovery from injury.
Postural Hand Synergies during Environmental Constraint Exploitation
The hypothesis that humans' ability to intuitively exploit the shape of an object and environmental constraints to achieve stable grasps and perform dexterous manipulations can be described in terms of a synergistic behavior in the generation of hand postures is formulated, i.e., using a reduced set of commonly used kinematic patterns.
The TU Hand: Using Compliant Connections to Modulate Grasping Behavior
This strategy allowed the retrieval of all objects from the basket, and scooping peas from the dish, but could not operate the hammer the syringe, or the scissors (as they required increased dexterity).
Coordination of multi-digit positions and forces during unconstrained grasping in response to object perturbations
It is proposed that digit forces were modulated online based on self-chosen digit locations during the holding phase in order to successfully compensate sudden external torques.
Analysis of Hand and Wrist Postural Synergies in Tolerance Grasping of Various Objects
Postural synergies of hand and wrist were presented separately through principal component analysis (PCA), expressed through the principal component (PC) information transmitted ratio, PC elements distribution and reconstructed angle error of joints.


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The results indicate that the hand is molded only gradually to the contours of an object to be grasped, and suggest that the specification of diverse aspects of a movement does not evolve at a uniform rate.
It is argued that a functional distinction should be made between palmar grips which immobilise an object in the hand, and digital patterns which permit manipulation, which are separate from any anatomically defined power and precision configurations.
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Principal components analysis showed that two components could characterize the hand postures used, irrespective of object size, and suggests that all of the degrees of freedom of the hand are controlled as a unit.
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For the purpose of classifying the patterns of static prehension in normal hands, the finger positions were photographed from 5 directions, while each of 7 normal adults held each of the 98 objects.
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It is shown that movements of the hand consist of two basic patterns of movements which are termed precision grip and power grip, which appear to cover the whole range of prehensile activity of the human hand.
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This chapter addresses the question faced by the controller, that of how best to use features of the hand to achieve the task goals, given anticipated object properties and predictable interaction outcomes.
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In studying grasping and manipulation we find two very different approaches to the subject: knowledge-based approaches based primarily on empirical studies of human grasping and manipulation, and
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Structural variables did not adequately predict shaping responses to real objects, as ascertained from Experiment 1, and the results have implications for cognitive representation of motor categories and hand shaping in response to objects.